Many conventional digital receivers use a forward error-correcting decoder, such as a low-density parity-check (LDPC) code decoder, to correct errors in the data that may occur during transmission. LDPC decoders can significantly reduce the probability of errors while allowing data transmission rates to approach the theoretical maximum Shannon limit. In many digital receivers, the LDPC decoder has been optimized under the assumption of additive white Gaussian noise (AWGN) in the channel. However, in many practical applications, the noise in communication channels is hardly ever white. For example, in satellite receiver channels, there may be correlated phase noise (e.g., a residual component after low frequency phase noise has been tracked out) and in terrestrial channels, there may be multi-path components. In orthogonal frequency division multiplexed (OFDM) receivers that perform equalization, even if the noise is white before equalization, it may not be white after equalization. This sub-optimal operation of an LDPC decoder in a digital receiver may result in increased power consumption and a decrease in signal-to-noise ratio (SNR) performance.
Thus, there are general needs for digital receivers and methods for improving the operations of forward error-correcting decoders. There are also needs for digital receivers that use less power and with increased SNR performance.